For some time now, manufacturers and users of cables and similiar articles have desired to protect their cables from the effects of abrasion. Abrasion inhibits the efficiency of a cable's performance and may lead to a total breakdown of a system employing such a cable. Additionally, safety considerations warrant that electrical cables and the like do not become abraided. Should an outer dielectric layer of a cable become frayed from abrasion, electrical power may become inadvertantly transmitted to the user of the system causing electrical shock or serious injury.
Abrasion stems primarily from two sources. The first source is during installation and use, objects may rub against a cable resulting in abrasion. The second source is other cables. It is very often desireable to bundle cables together. However, during installation or use one or more cables may be rubbed against one or more other cables in the the bundle which results in abrasion.
In order to satisfy industry needs with respect to both abrasion ane bundling there has been developed a number of products. One particular product is made by Bentley-Harris Manufacturing Company of Lionville, Pa. and sold under the federally registered trademark EXPANDO. EXPANDO sleeving is a braided tubular article made from a strong plastic material, such as polyester. The EXPANDO sleeving functions similiar to a "chinese finger" in that it is axially compressible and radially expansible and vice versa. In use, the cables or similiar articles are loaded into the sleeving by axially compressing the sleeve which causes the sleeve to radially expand. In addition, the overall length of the sleeving decreases in direct proportion to its radial expansion. As will be appreciated, this makes the loading operation considerably easier.
EXPANDO sleeving is very often used for bundling. A number of cables are loaded into the sleeving with the sleeve in its axially compressed and radially expanded condition. After loading, the sleeve is axially expanded and radially compressed to firmly hold the cables of the bundle in fixed relation to one another.
The EXPANDO sleeving prevents abrasion of the cable during installation by providing an outer surface other than the cable's own protective surface which can absorb the mechanical abuse of such installation. During use, the sleeving prevents one cable from rubbing against another cable by providing this protective outer layer between the cables. In bundling applications, the sleeving fixes the position of one cable relative to the another cable and thereby prevents internal bundle abrasion in use and installation.
While solving the above described problems quite satisfactorily, EXPANDO sleeving has been found to be lacking in one particular respect. As described above, when the sleeving compresses it radially expands. The radial expansion occurs generally in all directions and on an infinite number of planes. The radial expansion creates what amounts to buldge in the sleeving. When round cross-sectioned cable or other similiar articles are used, this buldge is not severe and is generally inconsequential. However, when flat cables or other similiar substrates are used, this buldging results in an inordinate amount of lost space.
Computer manufactures among others are greatly concerned with the efficient use of space. Very often the most limiting factor in computer hardware design is space. For this reason, among others, computer manufactures use ribbon cable or other flat cable. The tele-communications industry as well as other advanced technical industries such as robotics are also primary users of ribbon cable and the like flat substrates. Similiarly these advanced technical industries are often constrained by space requirements.
As will be appreciated by anyone looking at the rear of a computer mainframe, organization is critical. There are often tens of thousands of wires and literally hundreds of cable going from one place to the next. If the cables are disorganized and sloppy, a repairman's task may literally become impossible. Thusly, it is quite important to organize the cable and wire and present an organized appearance.
In order to solve the space and organizational problems of users of ribbon cable and other flat substrates, Applicant herein has developed the instant invention which comprises an abrasion resistant sleeve for flat substrates and a method of making same. In a preferred embodiment the sleeve is substantially similiar to EXPANDO sleeving with the added feature that the expansion and contraction of the sleeve occurs substantially on the same plane thereby, saving space. The sleeving in accordance with this invention includes means for permanently maintaining the sleeve in a flattened condition through expansion and contraction. The method of making the instant sleeve in a preferred embodiment provides for drawing the sleeving to a flatten condition to form two edges, bonding the edges which defines the maintaining means above and cutting the sleeving to the desired length.